1. Field of the Invention
The present invention relates to the field of a battery-powered hearing aid, and more particularly to an exterior power supply for a battery powered hearing aid.
2. Description of Related Art
A battery-powered hearing aid commonly requires button cell battery used as power source thereof. In general, the user replaces the button cell battery of the hearing aid when he or she can no longer hear sounds clearly. Most of the button cell batteries contain mercury, which is a pollution source. If the user uses the non-rechargeable battery, he or she has to pay more money to buy the button cell batteries.
Although some types of the button cell batteries are rechargeable, a capacity thereof is too small to provide a long use term so that the rechargeable button cell has to be often accessed from a battery container of the hearing aid. According to statistics, about 40% of hearing aid fixing is to replace a battery door of the battery container of the hearing aid.
With reference to FIGS. 7f and 7g of the US patent publication (Publication No. 2008/0311966 A1), a rechargeable battery assembly for a headset is proposed and has a casing 83a, a power conducting pole 82a, a power socket 36 and a power wire 38 with a power plug 37. The power socket is embedded inside the casing for receiving the power plug of the power wire 38 and electronically connected to the batteries 62 inside the casing. The casing uses the power socket so that a battery door is not required.
However, most of the hearing aids still have battery doors. The original problem of fixing battery doors frequently is not solved by the battery assembly of the cited US patent publication.
To overcome the shortcomings, the present invention provides an exterior power supply for hearing aid to mitigate or obviate the aforementioned problems.